HTML5: Edition for Web Authors

4.7.5 Edits and lists

The content models of the ol and ul
elements do not allow ins and del elements
as children. Lists always represent all their items, including items
that would otherwise have been marked as deleted.

To indicate that an item is inserted or deleted, an
ins or del element can be wrapped around
the contents of the li element. To indicate that an
item has been replaced by another, a single li element
can have one or more del elements followed by one or
more ins elements.

In the following example, a list that started empty had items
added and removed from it over time. The bits in the example that
have been emphasized show the parts that are the "current" state of
the list. The list item numbers don't take into account the edits,
though.